这是铁路各工区，专用的安全牌程序，是用LED显示屏的形式，指示出当前各工区的安全天数，目标安全天数以及实时时钟显示等，实际应用中。-This is the railway of the work area, private security licensing procedures is the use of LED displays the form of instructions from the current safety of the work area the number of d